That pipe they installed between here and France to allow businessmen to get to Brussels by train is about to be fully upgraded with 3G and 4G connections, with both Vodafone and EE claiming the depressing 35-minute offline plunge beneath the sea will feature full mobile access later this year.
From the wording of the announcement it appears that 2G and 3G services will appear first, with EE claiming it'll be ready to offer subsea 4G from the summer of this year. Both Vodafone and EE will only be providing access while on the North Tunnel, which takes passengers from the UK to France. When coming back, you'll have to roam on one of the French networks.
If you want to know how it came to pass, the Rail Engineer has put together a great piece on the history of Chunnel telecoms.
Image copyright Eurotunnel